1. Field of the Invention
This invention relates to an electrophotographic printer which makes a print mixed with data different in linear density.
2. Prior Art
In a conventional electrophotographic printer, the resolution is generally a dot density of 240 dots per inch (corresponding to a linear density of 9.4 lines/mm), and EDP (electronic data processing) data such as characters are formed with a dot density of 240 dpi (dots per inch). On the other hand, image data such as figures are generally read with the resolution of a dot density of 400 dots per inch (corresponding to a linear density of 16 lines/mm).
The conventional electrophotographic printer will be described with reference to FIGS. 1 and 2. FIG. 1 shows the arrangement of and electrophotographic printing system, and FIG. 2 is an explanatory diagram showing one example of a print which is to be made by the printing system.
A central processing unit (CPU) 12 applies EDP data having a dot density of 240 dpi to a print control unit 16. An image scanner 13 and a communication terminal 14 applies image data having a dot density of 400 dpi through an image data memory unit 15 to the print control unit 16. The data applied to the print control unit 16 are printed out with a dot density of 240 dpi by an electrophotographic printer 17.
When, in the above-described printing system, data different in dot density are printed out on one and the same page, the data supplied as image data of 400 dpi are printed out with a dot density of 240 dpi. Therefore, the printed image is larger than the original image, as a result of which it is lower in linear density; that is, it is low in picture quality. In the case where image data is read with a dot density of 240 dpi similarly as in the case of EDP image, the image read with an image scanner or the like is different in resolution from the original image, with the results that the printed image is different from the original image in impression, and is lower in picture quality.